Tamoxifen is used both to treat hormone-dependent breast cancer and to prevent the disease in women who have an elevated risk of breast cancer. Tamoxifen use has also been reported to increase a woman's risk of endometrial cancer, but the mechanism by which it may do this is not known.

One suggested mechanism involves the formation of tamoxifen-DNA adducts in endometrial tissue, although the presence of these adducts in endometrial tissue is controversial.

Frederick A. Beland, Ph.D., of the National Center for Toxicological Research in Jefferson, Ark., and colleagues used a new method called electrospray ionization-tandem mass spectrometry in addition to established methods to look for tamoxifen-DNA adducts in endometrial tissue from women who had and had not taken tamoxifen.

The researchers did not find any adducts and concluded that the formation of these adducts is not the mechanism by which tamoxifen causes endometrial cancer.

Their conclusion was reported in the Journal of the National Cancer Institute.

SOURCE:
Journal of the National Cancer Institute, July 21, 2004